A ceramic body mainly based on BaTiO.sub.3-based crystalline particles in which a part of Ba is substituted with at least one rare earth element and at least one alkaline earth metal element. The ceramic body contains from 1.0 to 8.0% by mass of Ba.sub.6Ti.sub.17O.sub.40 crystalline particles. The BaTiO.sub.3-based crystal particles have a substituted amount of one mol of the Ba with the alkaline earth metal element of 0.01 to 0.10 mol.

The disclosure relates to a PTC heating module for heating a fluid and a method for producing such a PTC heating module. The PTC heating module includes a plurality of PTC thermistors having main surfaces disposed opposite to one another and spaced apart relative to one another in a thickness direction. The PTC thermistors are arranged between two contact plates next to one another transversely to the thickness direction and spaced apart relative to one another. The main surfaces of the PTC thermistors are electrically contacted with a contact surface of the two contact plates. At least one dielectric function element is arranged between the two contact plates and laterally sealingly engages about the respective PTC thermistors to at least partially fill a hollow space between the two contact plates and facilitate enlarging a creepage distance between the two contact plates within the hollow space.

A PTC heating assembly includes a heating cell comprising a PTC element and conductor elements electrically abutting the PTC element. The heating cell is accommodated in a heater housing. The heater housing is manufactured with undersize relative to the heating cell so that the heating cell, after insertion into the heater housing, is held under pretension between mutually opposing walls of the heater housing. Accordingly, in the method according to the invention, the heater housing is elastically widened when the heating cell is inserted into the heater housing.

The present invention relates to a method for detecting overheating of an electrical heating device comprising a plurality of resistive elements configured to be supplied electrically using a control signal by pulse width modulation according to a setpoint, comprising the following steps:—detecting the setpoint,—detecting the duty cycle (PWM_system; PWM_subsystem),—defining a threshold value for detecting the duty cycle according to the setpoint, or a value of at least one parameter for monitoring an incidence of overheating—comparing the detected duty cycle value with the detection threshold value, and—detecting an incidence of overheating when the detected duty cycle value reaches the detection threshold value. The invention also relates to a corresponding control unit.

APTC heating assembly includes contact elements and a cuboid ceramic component on which a metallization is applied. The ceramic component comprises mutually opposing main side surfaces for heat dissipation which are larger by at least a factor of five than each of the end faces extending between the main side surfaces. The contact elements are electrically conductively connected to the metallization for introducing the power current into the ceramic component. The metallization is formed only on the main side surfaces and is in the form of elongated metallization strips. The metallization strips extend along mutually opposite edges of the cuboid ceramic component, are each assigned to one polarity, are separated by a single end face, and are connected to a power source via a common contact element.

An electric heating device includes an electric control device with a control housing that is in structural unity with a housing of a power section. The power section has a frame forming a heating chamber. At least one PTC heating device with at least one PTC element and conductor elements is provided in the heating chamber. The control housing forms a chamber which is separated from the frame by a partition wall. A heat sink projects from the partition wall into the power section. The electric control device has a printed circuit board and at least one power switch which generates a power loss and which is connected in a heat-conducting manner to a surface of a heat sink. An electrically insulating layer and a spring element, which holds the power switch applied under pretension against the surface of the heat sink, are provided between the power switch and the heat sink.

An electric heating device for a motor vehicle may include a heating volume and at least two spaced heating modules. A flow path of a fluid may lead through the heating volume. At least two spaced heating modules may be arranged in the heating volume. The at least two spaced heating modules may extend in a longitudinal direction. The at least two spaced heating modules may be spaced apart from one another in a transverse direction extending transversely to the longitudinal direction.

An electric heating device may include a heating volume, at least two heating modules arranged in the heating volume, an electrically conductive control housing, a power electronics, and an electrically conductive conductor arrangement. The control housing may delimit a control volume and may have a bottom that delimits the heating volume. The conductor arrangement may include an intermediate part electrically connected to the bottom and to an electrically conductive outer shell of each of the heating modules. The heating modules may each extend into the control volume through an associated passage opening of the bottom. The outer shell of each heating module may extend through an associated arrangement opening of the intermediate part. The conductor arrangement may include a cover covering the intermediate part. A closure bend of the intermediate part may extend through a cover opening of the cover and engage with the cover to form a form closure.

An operating method for an electric heater may include heating a fluid passing the electric heater to an outlet temperature by at least one heating element and operating the electric heater in one of a normal mode or a protection mode. In the normal mode, the at least one heating element may be supplied with at least one of a direct current and a direct voltage. In the protection mode, electrical power supplied to the at least one heating element may be regulated by pulse width modulation. The electric heater may be operated in the normal mode if a reference temperature is less than or equal to a critical temperature and in the protection mode if the reference temperature is greater than the critical temperature.

The invention relates to a heating device (1) for an air-conditioning housing, said heating device (1) comprising a heating body (2) supplied with current for heating an air flow passing through said heating body (2), said heating body (2) comprising heating elements through which said current passes and which are arranged in electrically insulated tubes (4) of the heating elements, said heating elements being controlled via a distribution unit (3), said heating device (1) comprising means for earthing a plurality of metal elements distributed in the heating body (2) and the distribution unit (3). Said heating device (1) is characterised in that said earthing means consist of a single earthing circuit which passes through the heating body (2) and the distribution unit (3) and is formed by arranging said metal elements in series with direct contact between said metal elements.